The PIXMA MX922 On-screen Manual will not install on macOS Catalina 10.15.7. Below is a screenshot of the error. The “MX920 series User Manual (Mac)” installer under “Optional Manual(s)” from Support Downloads doesn’t seem to be compatible with this OS. I sent an email notification last fall to the Contact -> Feedback link at the bottom of the About Consumer Support page, which is the only contact option I could find, but my report was not acknowledged.
Did all the other software (e.g. drivers) install OK? You can get the manual in PDF form which would be openable in the Preview application on macOS (or of course if you have Adobe's Acrobat Reader as well).
There's not a direct download of the PDF for this particular product, but after downloading the mpml-mac-mx920-1_3-en.dmg file from the Support Site and mounting that virtual drive on the Mac (double-click to open), it contained various PDFs you could then drag to your Mac's drives.
Yes, I should have mentioned that. I successfully installed software from 4 or 5 other .dmg image files from that same link and they all open and run just fine, including the PDF manual you mention, MX920 series (PDF) User Manual (Mac), from the mpml-mac-mx920-1_3-en.dmg file.
I'd like to be able to report the error to the tech team but that Feedback link doesn't seem to route to them.
The manual is also in web format. To access the manual, please use this link: